Data compression refers to a process in which algorithmic processing is performed on packet content, data amount is decreased, but information transfer is not affected. The data compression is for the purposes of conserving network transmission bandwidth and realizing application acceleration.
According to a CDC (Content-Defined Chunking) variable block algorithm, a duplicate database including a variable block, a fingerprint of the variable block, and a digest of the variable block is generated. After the duplicate database is generated, if to-be-compressed data includes a data fragment being the same as a first half of the variable block and being different from a second half of the variable block, a fingerprint of the data fragment and the fingerprint of the variable block match, and a digest of the data fragment and the digest of the variable block do not match. The CDC algorithm regards that the duplicate database needs to be updated, and uses a delimitation sliding window mechanism to generate a new variable block. Granularity of the new variable block may be large, which decreases the probability of subsequent to-be-compressed data matching the updated duplicate database. The above may incur decrease of compression efficiency.